1. Field of the Invention
The present invention relates to a board for an IC card for mounting an integrated circuit chip or the like.
2. Description of the Prior Art
An IC (integrated circuit) card comprises a board on which electronics components such as an IC chip of a memory device or a microprocessor are mounted. A board provided for producing an IC card may have one or more recesses on a plane thereof for mounting components. A board may be produced by injection molding. For example, after the components are fixed to the recess, resin is filled into the recesses to seal the components.
Such a board is described for example in Japanese Patent laid open Publication 62-298143/1987. In the production of the board, a plastic plate of a prescribed thickness is punched with a press to produce a card blank. Then, recesses for mounting components are cut in the blank precisely by a numerical control machine, to provide the board. However, the board produced as described above has a high production cost, and it is hard to reduce the cost even by mass production.
If the board is formed with injection molding with a plastics material at the same time as the recesses for mounting the components as an integral body, the production cost can be reduced largely. However, the thickness of the board is about 0.8 mm. Therefore, if the recesses are formed at the same time, the thickness at the bottom wall of the recesses becomes very thin, or the bottom walls cannot be formed surely. Therefore, cutting is adopted at present than injection molding.
However, if cutting is adopted, when an integrated circuit chip is fitted to the recess for adhesion, a portion of the recess to be adhered has a relatively smooth surface due to precise cutting. Therefore, when an IC card is subjected to a strong shock or when a card is bent, a part of adhesion plane is liable to be separated. In order to prevent the separation, the walls may be remained to have rough surfaces to increase adhesion strength. However, in such a case, precision along depth direction is liable to have a scattering, and precision of positions of connection terminals of integrated circuit chips cannot be maintained.